Nix the mini-nukes

The Bush administration's leaked Nuclear Posture Review suggests dramatic and dangerous changes in policy. Congress should reject a key result of it – the request for funds to study a new earth-penetrating nuclear weapon.

The review argues that the US must build a new generation of small nuclear weapons designed to penetrate deep into earth and destroy underground bunkers. The idea is that a nuclear weapon would penetrate so deep that its explosion would be contained, there would be no fallout, and a nuclear weapon that kills fewer people is somehow less nuclear. This is wrong – a nuke is a nuke.

The risk to the US incurred by use of nuclear weapons doesn't depend on their sizes. Dangerous states are deterred from nuclear use by the certainty they would invite US nuclear retaliation. This provides the US's best barrier against nuclear use. Any US use of a nuclear weapon would destroy that barrier and US moral leadership. The US would raise the probability that nuclear arms would be used against it.

A penetrating nuclear weapon of the sort the administration plans to study cannot be "clean." The depth the weapon can penetrate before detonating is limited by how hard the bomb or missile can hit the earth and still function. Calculations suggest that, using a weapon with one-third the power of the Hiroshima bomb, 650 feet of earth penetration is needed, but the best available missile technology can achieve far less than 100 feet. Such an explosion would eject large amounts of radioactive dirt.

We could get deeper penetration by landing troops above the bunker and boring a hole in the ground. But if we are to do that, we can use advanced conventional explosives or incendiary weapons to do the job.

• Henry C. Kelly is president of the Federation of American Scientists. Michael A. Levi runs its Nuclear Security Program.